A technique for performing a crosstalk compensation by MIMO processing on a wavelength division multiplexed optical signal propagating through an optical fiber transmission line having wavelength dispersion is known in the related art. A technique for applying MIMO processing to compensate for a crosstalk between spatially multiplexed signals and separate them from each other is also known. MIMO is an acronym for multiple input multiple output.
Related techniques are disclosed in, for example, Japanese Laid-Open Patent Publication No. 2016-100815 and International Publication Pamphlet No. WO 2015/052895.